2B : DIURETICS - CARBONIC ANHYDRASE INHIBITORS

Question 1

Carbonic
Anhydrase Inhibitors
prototype

Answer 1

Acetazolamide

Question 2

is an enzyme that helps
secrete cerebrospinal fluid and aqueous humor

Answer 2

Carbonic anhydrase

Question 3

MECHANISM OF ACTION OF CARBONIC ANHYDRASE INHIBITORS

Answer 3

Inhibits carbonic anhydrase
in brush border & cytoplasm

Block NaHCO3 reabsorption
in PCT

Question 4

Where is the action of carbonic anhydrase inhibitor

Answer 4

acts predominantly in PCT

Question 5

use of carbonic anhydrase inhibitor

Answer 5

1. In glaucoma,
   **secretion of aqueous humor is
   reduced **
2. in motion sickness, metabolic acidosis increases respiration

Question 6

Major Renal effect of
Acetazolamide

Answer 6

1. **BICARBONATE DIURESIS
   **
   body bicarbonate
   depletion metabolic acidosis
2. As increased Na+ reaches CCT
   excess Na+ is reabsorbed & K+ is secreted (**significant K+
   wasting )
3. Self limiting (2 3d)

Question 7

Acetazolamide as a Diuretic (use)

Answer 7

1. Edema
2. Cases resistant to diuretic
   monotherapy - combined with diuretics that block Na+ reabsorption at DCT marked natriuresis

Note: Long term use can lead to metabolic acidosis

Question 8

why is acetazolmaide not widely used in treatment of edema

Answer 8

low efficacy as a single agent

used for diuretic effect only if edema is accompanied by
significant* metabolic alkalosis*

Question 9

Therapeutic uses of CARBONIC ANHYDRASE

Answer 9

1. Open Angle Glaucoma
2. to correct Metabolic Alkalosis

Major clinical applications : on carbonic anhydrase dependent HCO3‾/fluid transport at** extrarenal sites**

Question 10

major indication OF CARBONIC ANHYDRASE

Answer 10

Open Angle Glaucoma

to lower
IOP (INTRAOCULAR PRESSURE)

• orally, parenterally , topical (dorzolamide brinzolamide)
• undetectable plasma levels
• no diuretic / systemic metabolic effects

Question 11

ADVERSE EFFECTS of carbonic anhydrase

Answer 11

1. Hyperchloremic Metabolic Acidosis
2. Calculus formation,
   ureteral colic

Question 12

• resulting from chronic HCO3 depletion
• persists as long as CAI (carbonic anhydrase inhibitor) is continued
• These agent cause acidosis since they force HCO3 out of the urine and so lose of bases leading to acidosis

Answer 12

Hyperchloremic Metabolic** Acidosis**

Question 13

urine
alkalinization may cause

Answer 13

Ca2+ salt precipitation and STONE FORMATION

Question 14

Carbonic Anhydrase Inhibitor can cause
what electrolytes in the urine

Answer 14

phosphaturia & hypercalciuria

Question 15

Adverse Effects of
Acetazolamide

Answer 15

Sulfonamides may cause
bone marrow depression, skin toxicity,** renal lesions, hypersensitivity**

Question 16

adverse effect of acetazolmaide in Large doses

Answer 16

drowsiness, paresthesias , renal calcium stones

Question 17

a problem with any PCT diuretic

Answer 17

Renal K+ wasting

Question 18

how to avoid renal K wasting in HF patient taking acetazolamide

Answer 18

use adenosine A1 receptor antagonists

Question 19

Carbonic Anhydrase Inhibitor in PCT act in what part of kidney

Answer 19

PCT
proximal convoluted tubule

Question 20

Uses:

Answer 20

Glaucoma,Mountain Sickness,
Eddema with alkalosis

Question 21

Side effects: Drowsiness,

Answer 21

Side effects: Drowsiness,
parestheisa , renal calcium stones, hyperchloremic metabolic acidosis,** hepatic enceph**

Question 22

Diuresis is self
limiting after

Answer 22

2-3 days